Control of grain boundary in alumina doped CCTO showing colossal permittivity by core-shell approach

2018 ◽  
Vol 38 (9) ◽  
pp. 3182-3187 ◽  
Author(s):  
Sonia De Almeida-Didry ◽  
Meledje Martin Nomel ◽  
Cécile Autret ◽  
Christophe Honstettre ◽  
Anthony Lucas ◽  
...  
2017 ◽  
Vol 62 (2) ◽  
pp. 1263-1266 ◽  
Author(s):  
M.-W. Lee ◽  
K.-H. Bae ◽  
S.-R. Lee ◽  
H.-J. Kim ◽  
T.-S. Jang

AbstractWe investigated the microstructural and magnetic property changes of DyCo, Cu + DyCo, and Al + DyCo diffusion-treated NdFeB sintered magnets. The coercivity of all diffusion treated magnet was increased at 880ºC of 1stpost annealing(PA), by 6.1 kOe in Cu and 7.0 kOe in Al mixed DyCo coated magnets, whereas this increment was found to be relatively low (3.9 kOe) in the magnet coated with DyCo only. The diffusivity and diffusion depth of Dy were increased in those magnets which were treated with Cu or Al mixed DyCo, mainly due to comparatively easy diffusion path provided by Cu and Al because of their solubility with Ndrich grain boundary phase. The formation of Cu/Al-rich grain boundary phase might have enhanced the diffusivity of Dy-atoms. Moreover, relatively a large number of Dy atoms reached into the magnet and mostly segregated at the interface of Nd2Fe14B and grain boundary phases covering Nd2Fe14B grains so that the core-shell type structures were developed. The formation of highly anisotropic (Nd, Dy)2Fe14B phase layer, which acted as the shell in the core-shell type structure so as to prevent the reverse domain movement, was the cause of enhancing the coercivity of diffusion treated NdFeB magnets. Segregation of cobalt in Nd-rich TJP followed by the formation of Co-rich phase was beneficial for the coercivity enhancement, resulting in the stabilization of the metastable c-Nd2O3phase.


Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3881 ◽  
Author(s):  
Yaojun Lu ◽  
Shuwei Zhong ◽  
Munan Yang ◽  
Chunming Wang ◽  
Liuyimei Yang ◽  
...  

The diffusion of Tb in sintered Nd-Fe-B magnets by the grain boundary diffusion process can significantly enhance coercivity. However, due to the influence of microstructures at different depths, the coercivity increment and temperature stability gradually decreases with the increase of diffusion depth, and exhibit good corrosion resistance at a sub-surface layer (300–1000 μm). According to the Electron Probe Micro-analyzer (EPMA) test results and the diffusion mechanism, the grain boundary and intragranular diffusion behavior under different Tb concentration gradients were analyzed, and the diffusion was divided into three stages. The first stage is located on the surface of the magnet, which formed a thick core-shell structure and a large number of RE-rich phases. The second stage is located in the sub-surface layer, forming a uniform and continuous RE-rich phase and thin core-shell structure. The third stage is located deeper in the magnet, and the Tb enrichment only existed at the triangular grain boundary.


2012 ◽  
Vol 74 ◽  
pp. 191-193 ◽  
Author(s):  
Yan Wang ◽  
Xihai Jin ◽  
Yangqiao Liu ◽  
Jing Sun ◽  
Lian Gao

2019 ◽  
Vol 96 ◽  
pp. 105943
Author(s):  
Sonia De Almeida-Didry ◽  
Cécile Autret ◽  
Anthony Lucas ◽  
François Pacreau ◽  
François Gervais

2020 ◽  
Vol 109 ◽  
pp. 106431 ◽  
Author(s):  
Sonia De Almeida-Didry ◽  
Samir Merad ◽  
Cécile Autret-Lambert ◽  
Meledje Martin Nomel ◽  
Anthony Lucas ◽  
...  

2018 ◽  
Vol 20 (1) ◽  
pp. 383-394 ◽  
Author(s):  
K. Rajouâ ◽  
L. Baklouti ◽  
F. Favier

Resistive hydrogen sensing performances and mechanism strongly depend on the Pt shell thickness in Pt@Au nanoparticle assemblies.


2020 ◽  
Vol 30 (12) ◽  
pp. 1908408 ◽  
Author(s):  
Pingli Qin ◽  
Tong Wu ◽  
Zhengchun Wang ◽  
Lan Xiao ◽  
Liang Ma ◽  
...  

2018 ◽  
Vol 6 (9) ◽  
pp. 2283-2294 ◽  
Author(s):  
Lingxia Li ◽  
Te Lu ◽  
Ning Zhang ◽  
Jiangteng Li ◽  
Zhaoyang Cai

The activation energies of the grain-boundary and different polarizations are researched to reveal the effect of the segregation structure on the performance.


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